Member for solid-state image pickup device and method for manufacturing solid-state image pickup device having first and second wiring structures with a concave portion between first and second substrates

ABSTRACT

A member for a solid-state image pickup device having a bonding plane with no gaps and a method for manufacturing the same are provided. The manufacturing method includes the steps of providing a first substrate provided with a photoelectric converter on its primary face and a first wiring structure, providing a second substrate provided with a part of a peripheral circuit on its primary face and a second wiring structure, and performing bonding so that the first substrate, the first wiring structure, the second wiring structure, and the second substrate are disposed in this order. In addition, at least one of an upper face of the first wiring structure and an upper face of the second wiring structure has a concave portion, and a conductive material forms a bottom face of the concave portion.

TECHNICAL FIELD

The present invention relates to a bonding portion of a solid-stateimage pickup device.

BACKGROUND ART

In CCD type and amplification-type solid-state image pickup devices usedfor digital still cameras, camcorders, and the like, in order to obtainhigh definition images, the sizes of pixels are required to be reduced.However, as the sizes of pixels are reduced more and more, a lightreceiving area of a photoelectric converter, in a pixel, detecting lightis decreased, and the sensitivity is decreased.

In PTL 1, a solid-state image pickup device has been disclosed in whichin a CMOS type solid-state image pickup device, which is anamplification-type solid-state image pickup device, in order to ensure alight receiving area of a photoelectric converter, a first substrateprovided with photoelectric converters and transfer transistors and asecond substrate provided with other circuits are bonded to each other.In addition, in the solid-state image pickup device disclosed in PTL 1,a technique has been disclosed in which copper bonding pads are usedwhen the first substrate and the second substrate are bonded together,and an insulating film around the copper bonding pads of the secondsubstrate is recessed.

CITATION LIST Patent Literature

PTL 1: Japanese Patent Laid-Open No. 2006-191081

SUMMARY OF INVENTION Technical Problem

However, in the bonding method disclosed in PTL 1, the relationshipbetween the coefficient of thermal expansion of the copper bonding padand that of the insulating film has not been studied, and a gap may begenerated at a bonding plane after the bonding. In addition, when a gapis generated around the copper bonding pad having a convex shape, copperforming the bonding pad may diffuse in some cases. When copper diffusesin the solid-state image pickup device, problems, such as generation ofwhite spots, may arise.

Accordingly, the present invention provides a member for a solid-stateimage pickup device having a bonding plane for solving the above problemand a method for manufacturing the solid-state image pickup device.

Solution to Problem

The present invention provides a method for manufacturing a solid-stateimage pickup device which comprises the steps of: providing a firstsubstrate provided with a photoelectric converter on its primary faceand a first wiring structure disposed on the primary face of the firstsubstrate;

providing a second substrate provided with, on its primary face, a partof a peripheral circuit including a control circuit and a readoutcircuit reading out a signal based on a charge of the photoelectricconverter and a second wiring structure disposed on the primary face ofthe second substrate; and performing boding so that the first substrate,the first wiring structure, the second wiring structure, and the secondsubstrate are disposed in this order. In the manufacturing methoddescribed above, at least one of an upper face of the first wiringstructure and an upper face of the second wiring structure has a concaveportion, and a conductive material forms a bottom face of the concaveportion.

In addition, the present invention provides a method for manufacturing asolid-state image pickup device which includes a first substrateprovided with, on its primary face, a photoelectric converter and atransfer transistor transferring a charge of the photoelectricconverter, a first wiring structure disposed on the primary face of thefirst substrate and having a first insulating film and a first bondingportion, a second substrate provided with, on its primary face, a partof a peripheral circuit portion including a control circuit and areadout circuit reading out a signal based on a charge of thephotoelectric converter, and a second wiring structure disposed on theprimary face of the second substrate and having a second insulating filmand a second bonding portion, in which the first substrate, the firstwiring structure, the second wiring structure, and the second substrateare disposed in this order, the method comprising:

a first step of forming the first insulating film and the first bondingportion on the first substrate; and a second step of forming the secondinsulating film and the second bonding portion on the second substrate.In the manufacturing method described above, in at least one of thefirst step and the second step, on the basis of the primary face of thefirst substrate, an upper face of the first bonding portion is lowerthan an upper face of the first insulating film; on the basis of theprimary face of the second substrate, an upper face of the secondbonding portion is lower than an upper face of the second insulatingfilm; or the upper face of the first bonding portion is lower than theupper face of the first insulating film on the basis of the primary faceof the first substrate, and the upper face of the second bonding portionis lower than the upper face of the second insulating film on the basisof the primary face of the second substrate.

Advantageous Effects of Invention

Accordingly, the present invention provides a member for a solid-stateimage pickup device having a bonding plane with no gaps and a method formanufacturing the solid-state image pickup device.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic cross-sectional view of a solid-state image pickupdevice according to Embodiment 1.

FIG. 2A is a schematic plan view of the solid-state image pickup deviceaccording to Embodiment 1.

FIG. 2B is a schematic plan view of the solid-state image pickup deviceaccording to Embodiment 1.

FIG. 3 is a circuit diagram of the solid-state image pickup deviceaccording to Embodiment 1.

FIG. 4A is a schematic cross-sectional view illustrating a step of amethod for manufacturing the solid-state image pickup device accordingto Embodiment 1.

FIG. 4B is a schematic cross-sectional view illustrating a step of themethod for manufacturing the solid-state image pickup device accordingto Embodiment 1.

FIG. 5A is a schematic cross-sectional view illustrating a step of themethod for manufacturing the solid-state image pickup device accordingto Embodiment 1.

FIG. 5B is a schematic cross-sectional view illustrating a step of themethod for manufacturing the solid-state image pickup device accordingto Embodiment 1.

FIG. 6A is a schematic cross-sectional view illustrating a step of themethod for manufacturing the solid-state image pickup device accordingto Embodiment 1.

FIG. 6B is a schematic cross-sectional view illustrating a step of themethod for manufacturing the solid-state image pickup device accordingto Embodiment 1.

FIG. 7A is a schematic cross-sectional view of a bonding portion of thesolid-state image pickup device according to Embodiment 1.

FIG. 7B is a schematic cross-sectional view of the bonding portion ofthe solid-state image pickup device according to Embodiment 1.

FIG. 7C is a schematic cross-sectional view of the bonding portion ofthe solid-state image pickup device according to Embodiment 1.

FIG. 7D is a schematic cross-sectional view of the bonding portion ofthe solid-state image pickup device according to Embodiment 1.

FIG. 7E is a schematic cross-sectional view of the bonding portion ofthe solid-state image pickup device according to Embodiment 1.

FIG. 8A is a schematic cross-sectional view of a bonding portion of asolid-state image pickup device according to Embodiment 2.

FIG. 8B is a schematic cross-sectional view of the bonding portion ofthe solid-state image pickup device according to Embodiment 2.

FIG. 8C is a schematic cross-sectional view of the bonding portion ofthe solid-state image pickup device according to Embodiment 2.

FIG. 8D is a schematic cross-sectional view of the bonding portion ofthe solid-state image pickup device according to Embodiment 2.

FIG. 8E is a schematic cross-sectional view of the bonding portion ofthe solid-state image pickup device according to Embodiment 2.

FIG. 9A is a schematic cross-sectional view of a bonding portion of asolid-state image pickup device according to Embodiment 3.

FIG. 9B is a schematic cross-sectional view of the bonding portion ofthe solid-state image pickup device according to Embodiment 3.

FIG. 9C is a schematic cross-sectional view of the bonding portion ofthe solid-state image pickup device according to Embodiment 3.

FIG. 9D is a schematic cross-sectional view of the bonding portion ofthe solid-state image pickup device according to Embodiment 3.

FIG. 9E is a schematic cross-sectional view of the bonding portion ofthe solid-state image pickup device according to Embodiment 3.

FIG. 10A is a schematic cross-sectional view illustrating a modificationof a bonding portion.

FIG. 10B is a schematic cross-sectional view illustrating a modificationof a bonding portion.

FIG. 10C is a schematic cross-sectional view illustrating a modificationof a bonding portion.

FIG. 10D is a schematic cross-sectional view illustrating a modificationof a bonding portion.

FIG. 10E is a schematic plan view illustrating the modification of thebonding portion.

FIG. 10F is a schematic plan view illustrating the modification of thebonding portion.

FIG. 10G is a schematic plan view illustrating the modification of thebonding portion.

FIG. 10H is a schematic plan view illustrating the modification of thebonding portion.

DESCRIPTION OF EMBODIMENTS

A method for manufacturing a solid-state image pickup device of thepresent invention has the steps of providing a first substrate providedwith photoelectric converters on its primary face and a first wiringstructure disposed on the primary face of the first substrate, andproviding a second substrate provided with a part of a peripheralcircuit on its primary face and a second wiring structure disposed onthe primary face of the second substrate. The method also has a step ofperforming bonding so that the first substrate, the first wiringstructure, the second wiring structure, and the second substrate aredisposed in this order. In addition, in this solid-state image pickupdevice, a concave portion is provided in at least one of an upper faceof the first wiring structure and an upper face of the second wiringstructure, and a bottom face of the concave portion includes aconductive material. By the structure as described above, a flat bondingplane can be obtained after the bonding.

Hereinafter, the present invention will be described in detail withreference to the drawings. In this embodiment, the primary face of thefirst substrate and the primary face of the second substrate aresubstrate surfaces on which transistors are formed. Opposite side faces(opposite side surfaces) facing the respective primary faces (primarysurfaces) are a back face (back surface) of the first substrate and aback face (surface) of the second substrate. In addition, an upwarddirection indicates a direction from the back face toward the primaryface of the substrate, and a downward direction and a depth directioneach indicate a direction from the primary face toward the back face ofthe substrate. Furthermore, an upward direction based on a certain basisindicates the height, and a downward direction based on a certain basisindicates the depth. In the following descriptions, when the first andsecond substrates are bonded with each other, the back face of thesecond substrate is at the bottom face and the back face of the firstsubstrate is at the top face.

Embodiment 1 of the present invention will be described with referenceto FIGS. 1 to 6B. First, a circuit of a solid-state image pickup deviceaccording to Embodiment 1 will be described with reference to FIG. 3. Inthis embodiment, the case in which a signal electric charge is anelectron will be described by way of example. The solid-state imagepickup device shown in FIG. 3 has a pixel portion 301 in which aplurality of photoelectric converters is arranged and a peripheralcircuit portion 302 having a peripheral circuit which includes a controlcircuit driving readout of a signal from the pixel portion 301 and asignal processing circuit processing a readout signal.

In the pixel portion 301, photoelectric converters 303, transfertransistors 304, amplification transistors 306, and reset transistors307 are arranged. A structure including at least one photoelectricconverter 303 is defined as a pixel. One pixel of this embodimentincludes one photoelectric converter 303, one transfer transistor 304,one amplification transistor 306, and one reset transistor 307. A sourceof the transfer transistor 304 is connected to the photoelectricconverter 303, and a drain region of the transfer transistor 304 isconnected to a gate electrode of the amplification transistor 306. Anode which is the same as the gate electrode of this amplificationtransistor 306 is defined as a node 305. The reset transistor 307 isconnected to the node 305 and sets the electric potential thereof to anarbitrary electric potential (such as, a reset electric potential). Inthis structure, the amplification transistor 306 is a part of a sourcefollower circuit and outputs a signal corresponding to the electricpotential of the node 305 to a signal line RL. The node 305 may also becalled a floating diffusion in some cases.

The peripheral circuit portion 302 indicates a region other than thepixel portion 301. In the peripheral circuit portion 302, a peripheralcircuit including a readout circuit and a control circuit is disposed.The peripheral circuit has a vertical scanning circuit VSR which is acontrol circuit supplying control signals to the gate electrodes of thetransistors of the pixel portion 301. In addition, the peripheralcircuit has a readout circuit RC which maintains signals outputted fromthe pixel portion 301 and performs signal processing, such asamplification, addition, and AD conversion. Furthermore, the peripheralcircuit has a horizontal scanning circuit HSR which is a control circuitcontrolling the timing for sequentially outputting signals from thereadout circuit RC.

In addition, the solid-state image pickup device according to Embodiment1 is formed by bonding two members to each other. The two members are afirst member 308 having a first substrate 101 and a second member 309having a second substrate 121. The photoelectric converters 303 and thetransfer transistors 304 of the pixel portion 301 are arranged on thefirst substrate, and the amplification transistors 306 and the resettransistors 307 of the pixel portion 301 and at least a part of theperipheral circuit are arranged on the second substrate. For example, acontrol signal from the peripheral circuit of the second member 309 tothe gate electrode of the transfer transistor 304 of the first member308 is supplied via a bonding portion 310. The structure of the bondingportion 310 will be described later.

A signal generated in the photoelectric converter 303 of the firstmember 308 is read out at the drain region of the transfer transistor304, that is, at the node 305. The node 305 includes the structureformed in the first member 308 and the structure formed in the secondmember 309.

According to the structure as described above, compared to a relatedcase in which all the pixel portion is disposed on one member (that is,on one large substrate), the area of the photoelectric converter 303 canbe increased, and hence the sensitivity can be improved. In addition,compared to the related case in which all the pixel portion is disposedon one member (that is, on one large substrate), when the area of thephotoelectric converter is not changed, the number of the photoelectricconverters 303 can be increased, and hence the number of pixels can beincreased. In addition, compared to the related case in which all thepixel portion and all the peripheral circuit portion are disposed on onemember (that is, on one large substrate), it becomes easy to separatelyform the pixel portion and the peripheral circuit portion.

A specific plan layout of the solid-state image pickup device asdescribed above will be described using schematic plan views of asolid-state image pickup device shown in FIGS. 2A and 2B. FIG. 2A showsa plan layout of the first member 308, that is, the first substrate 101,and FIG. 2B shows a plan layout of the second member 309, that is, thesecond substrate 121.

In FIG. 2A, in the first member 308, there are disposed a pixel portion301A in which photoelectric converters are arranged and pad portions312A in each of which pads 313 are arranged. In the pixel portion 301A,the photoelectric converters 303, the transfer transistors 304, thebonding portions 310, and bonding portions 311 shown in FIG. 3 aredisposed. In addition, bonding portions 314A for connection to thesecond member 309 are disposed at the same position as those of the pads313 when viewed along a direction perpendicular to the primary face ofthe substrate 101. An external terminal is connected to the pad 313. Thepads 313 are disposed in the solid-state image pickup device and includepads, each of which outputs a signal (image signal) based on a chargegenerated in the photoelectric converter, and pads to each of which avoltage or the like supplied from the outside to drive the peripheralcircuit is inputted.

Next, in FIG. 2B, a pixel portion 301B, the peripheral circuit portion302, and pad portions 312B are disposed in the second member 309. A partof a pixel circuit is disposed in the pixel portion 301B, and theamplification transistors 306, the reset transistors 307, and thebonding portions 310 and 311 shown in FIG. 3 are disposed therein. Apart of the peripheral circuit is disposed in the peripheral circuitportion 302, and the horizontal scanning circuits HSR, the verticalscanning circuits VSR, and the readout circuits RC are disposed therein.Bonding portions 314B for connection to the first member and protectivediode circuits 315 are disposed in the pad portions 312B.

In addition, the first member 308 and the second member 309 which havethe plan layouts shown in FIG. 2A and FIG. 2B, respectively, are bondedto each other to form the solid-state image pickup device of thisembodiment. In particular, the pixel portion 301A and the pixel portion301B are disposed so as to overlap with each other. In addition, thebonding portions 314A and the bonding portions 314B are bonded to eachother, and the bonding portions 310 and the bonding portions 311 of thefirst member are bonded to the bonding portions 310 and the bondingportions 311 of the second member, respectively. In addition, in FIGS.2A and 2B, a region of the first member 308 corresponding to aperipheral circuit portion 302B of the second member 309 is indicated bya peripheral circuit portion 302A. A part of the scanning circuit, thatis, a part of the peripheral circuit, may be disposed in the peripheralcircuit portion 302A. The structure of this bonding portion will bedescribed later in detail.

Next, the solid-state image pickup device shown in FIGS. 2A, 2B, and 3will be described with reference a schematic cross-sectional view shownin FIG. 1. In FIG. 1, the same constituent elements as those in FIGS.2A, 2B, and 3 are designated by the same reference numerals as thosedescribed above, and description will be omitted.

The first member 308 has a first wiring structure 149 and the firstsubstrate 101. The first substrate 101 is, for example, a siliconsemiconductor substrate and has a primary face 102 and a back face 103.The transistors are arranged on the primary face 102 of the firstsubstrate. The first wiring structure 149 has interlayer insulatingfilms 104 to 106, a gate electrode layer 107 containing gate electrodesand wires, wiring layers 109 and 111 containing wires, and contactlayers 108 and 110 containing contacts and/or vias. In this embodiment,the numbers of the interlayer insulating film, the wiring layer, and thecontact layer included in the first wiring structure 149 may bearbitrarily determined. In addition, the wiring layer 111 of the firstwiring structure 149 contains the bonding portions.

In the pixel portion 301 of the first member 308, an n-typesemiconductor region 112 forming the photoelectric converter, an n-typesemiconductor region 114 functioning as the drain of the transfertransistor, and an element isolation structure 119 are disposed in thefirst substrate 101. The transfer transistor is formed of the n-typesemiconductor region 112, the n-type semiconductor region 114, and agate electrode 113 contained in the gate electrode layer 107. A chargestored in the n-type semiconductor region 112 is transferred to then-type semiconductor region 114 by the gate electrode 113. An electricpotential based on the charge transferred to the n-type semiconductorregion 114 is transmitted to the second member 309 via the contact ofthe contact layer 108, the wire of the wiring layer 109, the via of thecontact layer 110, and the wire of the wiring layer 111. The wire ofthis wiring layer 111 forms the bonding portion 311. In addition, thephotoelectric converter may be a buried photodiode further having ap-type semiconductor region or a photogate and may be appropriatelychanged.

A planarizing layer 115, a color filter layer 116 containing a pluralityof color filters, a planarizing layer 117, and a microlens layer 118containing a plurality of microlenses are disposed in this order in thepixel portion 301 at a back face 103 side of the first substrate 101. InFIG. 1, although each of the color filters and each of the microlensesare provided for one photoelectric converter, that is, are provided ineach pixel, one color filter and one microlens may be provided for aplurality of pixels. The solid-state image pickup device of thisembodiment is a so-called back-side illumination-type solid-state imagepickup device in which light is incident from a microlens layer 118 sideand is received by a photoelectric converter.

In the pad portion 312A of the first member 308, the pads 313 andopenings 100 which expose the pads 313 for connection to an externalterminal are provided. In addition, the bonding portions 314A, each ofwhich transmits a voltage inputted from the pad 313 to the second member309, are disposed. In addition, in the first member 308, as shown inFIG. 1, an optional circuit element 120 may be provided in a regioncorresponding to the peripheral circuit portion 302B of the secondmember 309. Hereinafter, the bonding portion indicates a portion atwhich the conductive material of the first member and the conductivematerial of the second member, which collectively form an electricalconnection, are boned to each other and also indicates the conductivematerial before bonding.

The second member 309 has a second wiring structure 150 and the secondsubstrate 121. The second substrate 121 is, for example, a siliconsemiconductor substrate and has a primary face 122 and a back face 123.The transistors are arranged on the primary face 122 of the secondsubstrate. The second wiring structure 150 has interlayer insulatingfilms 124 to 127, a gate electrode layer 128 containing gate electrodesand wires, wiring layers 130, 132, and 134 containing wires, and contactlayers 129, 131, 133 containing contacts and/or vias. In thisembodiment, the numbers of the interlayer insulating film, the wiringlayer, and the contact layer included in the second wiring structure 150may be arbitrarily determined. In addition, the wiring layer 134contains the bonding portions.

In the pixel portion 301 of the second member 309, a well 135 formingthe amplification transistor which forms the pixel circuit, an n-typesemiconductor region 138 forming source/drain regions of theamplification transistor, and an element isolation structure 136 aredisposed in the second substrate 121. The amplification transistor isdisposed in the well 135 and is formed of a gate electrode 137 containedin the gate electrode layer 128 and the n-type semiconductor region 138forming the source/drain regions. In this embodiment, the bondingportion 311 of the first member 308 and the gate electrode 137 of theamplification transistor are connected to each other through the wire ofthe wiring layer 134, the via of the contact layer 133, the wire of thewiring layer 132, the via of the wiring layer 131, the wire of thewiring layer 130, and the contact of the contact layer 129. In thiscase, the node 305 shown in FIG. 3 is formed of the n-type semiconductorregion 114, the wires of the wiring layers 109, 111, 134, 132, and 130,the contacts and/or vias of the contact layers 108, 110, 133, 131, and129, and the gate electrode 137 shown in FIG. 1. Other circuits (such asthe reset transistor) of the pixel portion 301 are not shown in thefigure.

Next, at least a part of the peripheral circuit including the controlcircuits, such as the horizontal scanning circuit and the verticalscanning circuit, and the readout circuits is disposed in the peripheralcircuit portion 302B of the second member 309. FIG. 1 shows an n-typetransistor and a p-type transistor in an optional circuit included inthe peripheral circuit. An n-type transistor formed of a gate electrode140 contained in the gate electrode layer 128 and n-type source/drainregions 141 is disposed in a p-type well 139. In addition, a p-typetransistor having a gate electrode 143 contained in the gate electrodelayer 128 and a p-type semiconductor region 144 forming p-typesource/drain regions is disposed in an n-type well 142.

In addition, in the pad portion 312B of the second member 309, there aredisposed the protective diode circuit 315 inputting a signal from thepad 313 of the first member 308 and the bonding portion 314B for bondingto the first member 308. Two diodes 145 and 146 each formed from thesemiconductor region and two resistors 147 and 148 formed from the gateelectrode layer 128 are contained in the protective diode circuit 315 ofthis embodiment. However, a commonly-used protective diode circuit canbe applied to the protective diode circuit 315.

In addition, in the solid-state image pickup device according to thisembodiment, the primary face 102 of the first substrate 101 and theprimary face 122 of the second substrate 121 are disposed to face eachother with the first and second wiring structures provided therebetween(facing arrangement). That is, the first substrate, the first wiringstructure, the second wiring structure, and the second substrate aredisposed in this order. In addition, it can also be the that an upperface of the first wiring structure 149 and an upper face of the secondwiring structure 150 are bonded to each other at a bonding plane X. Thatis, the first member 308 and the second member 309 are bonded to eachother at the bonding plane X. The bonding plane X is formed from theupper face of the first wiring structure 149 and the upper face of thesecond wiring structure 150. In addition, the pad 313 of the solid-stateimage pickup device for exchanging a signal with the outside is disposedabove the primary face 122 of the second member 309, and the opening 100is provided at a first member 308 side.

In this embodiment, in the first wiring structure 149, the wiring layer109 is formed of wires (aluminum wires) primarily composed of aluminum,and the wiring layer 111 is formed of wires (copper wires) primarilycomposed of copper. In addition, in the second wiring structure 150, thecontact layer 131 and the wiring layer 132 are formed of aluminum wires,and the wiring layer 134 is formed of copper wires. In this case, thebonding portion 311 and the bonding portion 314A contained in the wiringlayer 111 formed of copper wires are bonded to the bonding portion 311and the bonding portion 314B contained in the wiring layer 134 formed ofcopper wires, respectively, at the bonding plane X by metal bonding. Inaddition, in the pad portion, the pad 313 for connection to an externalterminal is disposed in the same layer as that of the wiring layer 109,that is, at the same height as that thereof, and is a conductivematerial primarily composed of aluminum. Incidentally, the height is aheight from the primary face 102 of the first substrate 101.

Next, a method for manufacturing the solid-state image pickup device ofthis embodiment will be described with reference to FIGS. 4A to 6B.FIGS. 4A and 4B are each a schematic cross-sectional view showing a stepof manufacturing the first member 308. FIGS. 5A and 5B are each aschematic cross-sectional view showing a step of manufacturing thesecond member 309, and FIGS. 6A and 6B are each a schematiccross-sectional view showing a manufacturing step performed after thefirst member 308 and the second member 309 are bonded to each other.

Steps of manufacturing the first member 308 shown in FIG. 1 will bedescribed with reference to FIGS. 4A and 4B. In FIGS. 4A and 4B, astructure to be later formed into the first member 308 shown in FIG. 1is represented by 308′, and portions to be formed into the pixel portion301, the peripheral circuit portion 302, the pad portion 312, and thecircuit element 120, which is a part of the peripheral circuit, shown inFIG. 1 are represented by 301′, 302′, 312′, and 120′, respectively.

First, a semiconductor substrate is provided, and elements are formed inthe semiconductor substrate. A semiconductor substrate 401 of athickness D3 having a primary face 402 and a back face 403 is provided.The semiconductor substrate 401 is, for example, a silicon semiconductorsubstrate. The element isolation structure 119 is formed in thesemiconductor substrate 401. The element isolation structure 119contains an insulating material, such as a silicon oxide film, and has,for example, a LOCOS or an STI structure. In addition, a well (notshown) having an arbitrary conductivity type is formed in thesemiconductor substrate 401. Subsequently, the n-type semiconductorregions 112 and 114 and a p-type semiconductor region (not shown), whichform a photoelectric converter and a transistor, are formed. Inaddition, the gate electrode layer 107 containing the gate electrode 113of the transfer transistor is formed. The gate electrode layer isformed, for example, by deposition and patterning of a polysilicon layerand may contain a wire as well as the gate electrode. Methods forforming the gate electrode, element isolation, and semiconductor regionmay be performed in accordance with a general semiconductor process, anddetailed description will be omitted. The structure shown in FIG. 4A isobtained by the steps described above.

Next, the wiring structure is formed on the primary face 402 of thesemiconductor substrate 401. The wiring structure has an interlayerinsulating film 104′, the interlayer insulating films 105 and 106, thecontact layers 108 and 110, and the wiring layers 109 and 111. In thisembodiment, the interlayer insulating film 104′ is later formed into theinterlayer insulating film 104 shown in FIG. 1. The interlayerinsulating film 104′ covers the gate electrode layer 107, the contactlayer 108 is disposed in the interlayer insulating film 104′, and thewiring layer 109 is disposed on the interlayer insulating film 104′. Inaddition, the interlayer insulating film 105 covers the wiring layer109, the contact layer 110 is disposed in the interlayer insulating film105, the wiring layer 111 is disposed on the interlayer insulating film105, and the interlayer insulating film 106 is disposed on theinterlayer insulating film 105 and has openings to expose the wires ofthe wiring layer 111. The upper face of the wiring structure is formedof the upper face of the interlayer insulating film 106 and the upperface of the wiring layer 111.

In this embodiment, the interlayer insulating films 104′, 105, and 106are each a silicon oxide film. However, the interlayer insulating films104′, 105, and 106 may also be formed, for example, of a silicon nitridefilm or an organic resin. The contact 108 and the via 110 are formed,for example, from tungsten. The wiring layer 109 is formed of wiresprimarily composed of aluminum, and the wiring layer 111 is formed ofwires primarily composed of copper. The wiring layer 111 contains thebonding portion 314A and a bonding portion 311A, and the wiring layer109 contains the pad 313. The wires of the wiring layer primarilycomposed of copper can be formed by a single damascene method in whichafter a groove is formed in the interlayer insulating film, a barriermetal and/or copper is filled in the groove. The wires of the wiringlayer primarily composed of aluminum can be formed by patterning abarrier metal and/or an aluminum film formed on the interlayerinsulating film using a photolithographic and an etching technique.Methods for manufacturing these wiring layer, contact layer, andinterlayer insulating film can be performed in accordance with a generalsemiconductor process, and detailed description will be omitted. Thestructure shown FIG. 4B is obtained by the steps described above. InFIG. 4B, the portions represented by reference numerals 104′, 105, 106,108, 109, 110, and 111 are later used to form the first wiring structure149 shown in FIG. 1. In addition, the bonding portion 311A later formsthe bonding portion 311.

In this FIG. 4B, the upper face of the first wiring structure 149 whichlater forms the bonding plane X shown in FIG. 1 is formed of the upperface of the interlayer insulating film 106 and the upper face of eachwire of the wiring layer 111. The structure of this upper face formingthis bonding plane X will be described later in detail.

Next, steps of manufacturing the second member 309 shown in FIG. 1 willbe described with reference to FIGS. 5A and 5B. In FIGS. 5A and 5B, astructure to be later formed into the second member 309 shown in FIG. 1is represented by reference numeral 309′, and portions to be formed intothe pixel portion 301, the peripheral circuit portion 302, the padportion 312, and the protective diode circuit 315 shown in FIG. 1 arerepresented by reference numerals 301′, 302′, 312′, and 315′,respectively.

First, a semiconductor substrate is provided, and elements are formed inthe semiconductor substrate. A semiconductor substrate 404 of athickness D4 having a primary face 405 and a back face 406 is provided.Next, the element isolation structure 136 is formed in the semiconductorsubstrate 404 using a LOCOS or an STI structure. In addition, the p-typewells 135 and 139 and the n-type well 142 are formed in thesemiconductor substrate 404. Subsequently, the n-type semiconductorregions 138 and 141 and the p-type semiconductor region 144, each ofwhich is to be formed into the source/drain regions of the transistor,and a semiconductor region forming a diode are formed. In addition, thegate electrode layer 128 containing the gate electrodes 137, 140, and143 of the transistors and wires (resistors) is formed by deposition andpatterning of a polysilicon layer. In this case, methods for forming thegate electrode, element isolation, and semiconductor region can beperformed in accordance with a general semiconductor process, anddetailed description will be omitted. The structure shown in FIG. 5A isobtained by the steps described above.

Next, the wiring structure is formed on the primary face 405 of thesemiconductor substrate 404. The wiring structure has the interlayerinsulating films 124 to 127, the contact layers 129, 131, and 133, andthe wiring layers 130, 132, and 134. The interlayer insulating film 124covers the gate electrode layer 128, the contact layer 129 is disposedin the interlayer insulating film 124, and the wiring layer 130 isdisposed on the interlayer insulating film 124. In addition, theinterlayer insulating film 125 covers the wiring layer 130, the contactlayer 131 is disposed in the interlayer insulating film 125, the wiringlayer 132 is disposed on the interlayer insulating film 125, and theinterlayer insulating film 126 is disposed on the interlayer insulatingfilm 125 to cover the wiring layer 132. In addition, the contact layer133 is disposed in the interlayer insulating film 126, the wiring layer134 is disposed on the interlayer insulating film 126, and theinterlayer insulating film 127 is disposed on the interlayer insulatingfilm 126 and also has openings to expose the wiring layer 134. The upperface of the wiring structure is formed of the upper face of theinterlayer insulating film 127 and the upper face of the wiring layer134.

In this case, the interlayer insulating films 124 to 127 are each asilicon oxide film. The interlayer insulating films 124 to 127 may alsobe formed, for example, of a silicon nitride film or an organic resin.The contact 129 and the vias 131 and 133 are formed, for example, oftungsten. The wiring layers 130 and 132 are each formed of wiresprimarily composed of aluminum, and the wiring layer 134 is formed ofwires primarily composed of copper. The wiring layer 134 contains thebonding portion 314B and a bonding portion 311B. The wires of the wiringlayer primarily composed of copper can be formed by a single damascenemethod in which after a groove is formed in the interlayer insulatingfilm, a barrier metal and/or copper is filled in the groove. The wiresof the wiring layer primarily composed of aluminum can be formed bypatterning a barrier metal and/or an aluminum film formed on theinterlayer insulating film using a photolithographic and an etchingtechnique. Methods for manufacturing these wiring layer, contact layer,and interlayer insulating film can be performed in accordance with ageneral semiconductor process, and detailed description will be omitted.Accordingly, the structure shown in FIG. 5B is obtained by the stepsdescribed above. In FIG. 5B, the portions represented, for example, byreference numerals 124 to 127 and 129 to 134 are later used to form thesecond wiring structure 150 shown in FIG. 1. In addition, the bondingportion 311B later forms the bonding portion 311.

In this FIG. 5B, the upper face of the second wiring structure whichlater forms the bonding plane X shown in FIG. 1 is formed of the upperface of the interlayer insulating film 127 and the upper face of eachwire of the wiring layer 134. The wiring layer 134 is also a conductivematerial to be used as the bonding portion. That is, the upper face ofthe second wiring structure contains the upper face of the conductivematerial. The structure of the upper face of this second wiringstructure will be described later in detail.

The first member 308′ and the second member 309′ as shown in FIGS. 4Band 5B, respectively, are bonded together so that the primary face 402and the primary face 405 of the respective semiconductor substrates faceeach other. That is, the uppermost face of the wiring structure of thefirst member 308′ and the uppermost face of the wiring structure of thesecond member 309′ are boned to each other. In this embodiment, sincethe bonding portions 311A and 311B and the bonding portions 314A and314B are formed of wires primarily composed of copper, when bonding isperformed therebetween, metal bonding of copper may be performed. Bythis bonding, besides the metal bonding of copper, the bonding is alsoperformed between the insulating films. Accordingly, the two wiringstructures are formed into one wiring structure containing the bondingportions.

After the first member 308′ and the second member 309′ are bondedtogether, the thickness of the semiconductor substrate 401 of the firstmember 308′ is reduced at a back face 403 side. The reduction of thethickness may be performed by CMP or etching. Accordingly, thesemiconductor substrate 401 is formed into a semiconductor substrate407, and the thickness is changed from D3 to D1 (D1<D3) (FIG. 6A). Asdescribed above, since the thickness of the semiconductor substrate 401is reduced to form the semiconductor substrate 407, subsequently,incident light is able to efficiently enter the photoelectric converter.In addition, at this stage, the thickness D1 of the semiconductorsubstrate 407 is smaller than the thickness D4 of the semiconductorsubstrate 404.

Next, a planarizing layer 409 formed of a resin, a color filter layer410, a planarizing layer 411 formed of a resin, and a microlens layer412 are formed in this order on a back face 408 of the semiconductorsubstrate 407. Methods for manufacturing these planarizing layer, colorfilter layer, and microlens layer can be performed in accordance with ageneral semiconductor process, and detailed description will be omitted.In this case, the microlens layer may be formed to the region 312′ whichis to be formed into the pad portion. The structure shown in FIG. 6B isobtained by the steps described above.

In addition, the opening 100 is formed to expose the pad 313. In thisstep, a photoresist mask having an arbitrary opening is formed on themicrolens layer 412 using a photolithographic technique. In addition,using a dry etching technique, the microlens layer 412, the planarizinglayer 411, the color filter layer 410, the planarizing layer 409, thesemiconductor substrate 407, and the interlayer insulating film 104′ arepartially removed, thereby forming the opening 100 to expose the pad313.

Accordingly, the microlens layer 118, the planarizing layers 117 and115, the color filter layer 116, the first substrate 101, and theinterlayer insulating film 104 are formed. As a result, the structureshown in FIG. 1 is obtained. The semiconductor substrate 404, theprimary face 405, the back face 406, and the thickness D4 shown in FIG.6B correspond to the second substrate 121, the primary face 122, theback face 123, and the thickness D2 shown in FIG. 1, respectively.Although the thickness D4 is not changed from the thickness D2 in thiscase, the thickness of the semiconductor substrate 404 may be reduced sothat the thickness D2 is smaller than the thickness D4. Although thenumber of steps is increased by the reduction in thickness, thesolid-state image pickup device can be miniaturized.

Hereinafter, a process for forming the bonding plane X will be describedwith reference to FIGS. 7A to 7E, focusing on the bonding portion 311A(first bonding portion) shown in FIG. 4B and the bonding portion 311B(second bonding portion) shown in FIG. 5B. FIGS. 7A to 7E are each across-sectional view focusing on the bonding portion. The description ofthe structure other than the bonding portion will be omitted.

First, a process for forming the bonding portion 311B shown in FIG. 5Bwill be described from the beginning. FIG. 7A shows one bonding portion311B. First, after a film to be formed into the interlayer insulatingfilm 127 is formed, a groove to be used for the wire is formed in theinterlayer insulating film 127. Next, a film of a conductive material701 and a film of a barrier metal 702, each of which forms the bondingportion, are formed in the groove in the interlayer insulating film 127.Excessive films of the conductive material 701 and the bather metal 702are removed by CMP or the like, thereby forming the structure shown inFIG. 7A. In this case, the conductive material contains copper as aprimary component, and the barrier metal contains tantalum and/ortitanium. A method for forming this conductive material 701 and thebarrier metal 702 is a single damascene method, and more detaileddescription will be omitted.

Next, by wet etching, dry etching, or CMP, the conductive material 701is partially removed to form the bonding portion 311B shown in FIG. 7B.This step of partially removing the conductive material 701 may besimultaneously performed with the step of removing the excessive filmsof the conductive material 701 and the barrier metal 702 in the singledamascene method described above. The bonding portion 311B shown in FIG.7B contains a conductive material 707 and a barrier metal 708. In FIG.7B, the second wiring structure of the second member 309′ has a concaveportion 704 in the upper face. The upper face of the second wiringstructure of the second member 309′ is formed of an upper face 703 ofthe interlayer insulating film 127 (second insulating film) and an upperface 706 of the bonding portion 311B. A bottom face of the concaveportion 704 is the upper face 706 of bonding portion 311B, and theinterlayer insulating film 127 is exposed at a side face 705 of theconcave portion 704. A step d1 is formed between the upper face 703 ofthe interlayer insulating film 127 and the upper face 706 of the bondingportion 311B. This structure shown in FIG. 7B is the structure shown inFIG. 5B. Although description is performed with reference to FIG. 7Bfocusing on one of the bonding portions 311B, it is assumed that everybonding portion disposed in the upper face of the second wiringstructure is processed in a manner similar to that described above andhas a similar structure to that described above. In addition, thebarrier metal 702 may also be partially removed when the conductivematerial 701 is partially removed.

Next, as shown in FIG. 7C, in a mixed gas atmosphere of oxygen andnitrogen, plasma irradiation 709 is performed on the upper face of thesecond member 309′, that is, on the upper face of the second wiringstructure, so that the face thereof is activated. By performing thisplasma irradiation, compared to the case in which plasma irradiation isnot performed, bonding between the interlayer insulating films, such asa silicon oxide film and/or a silicon nitride film, can be morestrengthened. In addition, instead of using plasma irradiation, anactivation method by a chemical treatment may also be used.

Hereinafter, in FIGS. 7D and 7E, the bonding steps shown in FIGS. 6A and6B will be described in detail. First, the second member 309′ processedby the treatment shown in FIG. 7C and the first member 308′ processed ina manner similar to that performed on the second member 309′ as shown inFIGS. 7A to 7C are provided and are bonded together as shown in FIG. 7D.The upper face of the first wiring structure of the first member 308′has the upper face of the interlayer insulating film 106 (firstinsulating film) and an upper face 711 of the bonding portion 311A andhas a concave portion. A bottom face of the concave portion is the upperface 711 of the bonding portion 311A, and the interlayer insulating film106 is exposed at a side face 710 of the concave portion. In addition,the upper face of the interlayer insulating film 106 and the upper face711 of the bonding portion 311A form a step d2. The first member 308′and the second member 309′ as described above are bonded together toform the bonding plane X. A heat treatment is performed when the bondingis performed. Accordingly, the bonding portions 311A and 311B are bondedtogether, the interlayer insulating films 106 and 127 are bondedtogether, and as a result, the bonding portion 311 as shown in FIG. 6Ais formed (FIG. 7E). In addition, from the step shown in FIG. 7A to thestep shown in FIG. 7E, the process is preferably performed in a vacuumor an inert gas atmosphere. The reason for this is to prevent the upperfaces of the bonding portion 311A and 311B from being oxidized.

Since the bonding portion 311A and the bonding portion 311B are eachformed to have a concave portion, a flat bonding plane X with no gapscan be formed in the bonding step shown in FIG. 7D. The reason for thisis that, in general, a conductive material, such as copper, forming abonding portion has a high coefficient of thermal expansion as comparedto that of an insulating material, such as a silicon oxide or a siliconnitride film, forming an interlayer insulating film. As for thecoefficient of thermal expansion (×10⁻⁶/K), for example, copper has16.8, a silicon oxide film has 0.6 to 0.9, and a silicon nitride filmhas 2.8 to 3.2. Accordingly, when the bonding portion 311A and thebonding portion 311B are each formed to have a concave portion asdescribed in this embodiment, a flat bonding plane X can be formed.

The present invention is not limited to the steps described in themanufacturing method according to this embodiment, and the order of thesteps may also be changed. In addition, the order of manufacturing thefirst member 308 and the second member 309 may be appropriatelydetermined. Furthermore, an SOI substrate may also be applied to each ofthe semiconductor substrates 401 and 404.

In addition, it is also possible that the first member 308 and thesecond member 309 are separately provided as the substrates for thesolid-state image pickup device and are then bonded together. Forexample, there may be mentioned a first member having a first substrateand a first wiring structure which has a wiring layer containing wiresprimarily composed of copper and a wiring layer containing wiresprimarily composed of aluminum. In this case, the upper face of at leastone of the members may have the structure as shown in FIG. 7B. Byproviding the first member or the second member as described above, thesolid-state image pickup device of this embodiment can be manufactured.

Next, Embodiment 2 of the present invention will be described withreference to FIGS. 8A to 8E. FIGS. 8A to 8E are cross-sectional viewscorresponding to FIGS. 7A to 7E, respectively, focusing on the bondingportion. In FIGS. 8A to 8E, constituent elements similar to those shownin FIGS. 7A to 7E are designated by the same reference numerals as thosedescribed above, and description will be omitted. The point of thisembodiment different from that shown in FIGS. 7A to 7E is that as shownin FIG. 8D, the upper face of the first wiring structure of the firstmember 308′ has not a concave portion and is flat.

FIGS. 8A to 8C are the same views as those of FIGS. 7A to 7C,respectively, and the same treatments as those shown FIGS. 7A to 7C areperformed on the second member 309′. In Embodiment 1, although the firstmember 308′ is also processed in a manner similar to that performed onthe second member 309′, the first member 308′ is not processed in thisembodiment. That is, the upper face of the first wiring structure of thefirst member 308′ is formed of the upper face of the bonding portion311A (wiring layer 111) and the upper face of the interlayer insulatingfilm 106, so that the upper face is flat and has no concave portion. Thefirst member 308′ and the second member 309′ as described above arebonded to each other, so that the bonding plane X is formed. The othersteps are the same as those described with reference to FIGS. 7A to 7Eof Embodiment 1. In this embodiment, the bonding portion 311A has aconductive material 801 and a barrier metal 802.

When the upper face of at least one of the members has a concaveportion, the bottom face of which is the bonding portion, the generationof gaps at the bonding plane can be suppressed which is caused by thedifference in thermal expansion between the materials at the bonding.

Next, Embodiment 3 of the present invention will be described withreference to FIGS. 9A to 9E. FIGS. 9A to 9E are schematiccross-sectional views, focusing on the bonding portion, corresponding tothose shown in FIGS. 7A to 7E, respectively. In FIGS. 9A to 9E,constituent elements similar to those shown in FIGS. 7A to 7E aredesignated by the same reference numerals as those described above, anddescription will be omitted.

In FIGS. 9A to 9C, the second member 309′ is processed so that thebonding portion of the upper face of the second wiring structure has aconvex shape. That is, in FIG. 9A, the second member 309′ has aninterlayer insulating film 901, a conductive material 902, and a barriermetal 903, the latter two of which are to be formed into the bondingportion 311B, similar to those shown in FIG. 7A.

Next, the interlayer insulating film 901 is partially removed by wetetching, dry etching, or a CMP treatment. As shown in FIG. 9B, theinterlayer insulating film 127 is formed, and the conductive material902 functioning as the bonding portion forms a convex portion. That is,the upper face of the second wiring structure contains an upper face 904of the interlayer insulating film 127 and an upper face 905 of thebonding portion 311B and has a convex portion 906. The upper face of theconvex portion 906 is the upper face 905 of the bonding portion 311B,and the bonding portion 311B is exposed at a side face of the convexportion. In addition, the upper face 904 of the interlayer insulatingfilm 127 and the upper face 905 of the bonding portion 311B form a stepd3. Furthermore, as in the case shown in FIG. 7C, plasma irradiation 907is performed on the upper face of the second wiring structure (FIG. 9C).Next, although not shown in the figure, treatments similar to thoseshown FIGS. 7A to 7C are performed on the first member 308′. That is,the upper face of the first member 308′ has a concave portion. The firstmember 308′ and the second member 309′ as described above are bonded atthe bonding plane X, thereby forming the bonding portion 311 shown inFIG. 9E.

As described above, since the upper face of at least one of the membershas a concave portion, the bottom face of which is the bonding portion,even if the convex portion is provided on the upper face of the othermember, the generation of gaps at the bonding plane can be suppressedwhich is caused by the difference in thermal expansion between thematerials at the bonding.

Next, the structure of the bonding portion of each of the aboveembodiments, that is, the structure of the upper face of the first orthe second wiring structure, will be described with reference to FIGS.10A to 10H. FIGS. 10A to 10D are each a schematic cross-sectional viewof the concave portion of the upper face of the second wiring structure,and FIGS. 10E to 10H are each a schematic plan view thereof. Theschematic plan view shows a layout of elements on the upper face of thesecond wiring structure, and the schematic cross-sectional view showsthe cross-section of that shown in the schematic plan view taken alongthe line of each figure. In FIGS. 10A to 10H, constituent elementsdescribed in Embodiments 1 to 3 are designated by the same referencenumerals as those described above, and description will be omitted.

FIG. 10A shows the same structure as that shown in FIG. 7B, and FIG. 10Eis a schematic plan view corresponding to that shown in FIG. 10A. Asshown in the schematic plan view of FIG. 10E, it is found that the areaof the concave portion 704 is almost the same as that of the bondingportion 311B. This structure is applicable to the concave portion of thepresent invention.

Next, Modification 1 will be described with reference to FIGS. 10B and10F. FIGS. 10B and 10F are a schematic cross-sectional view and aschematic plan view, respectively, corresponding to each other and showthe structure in which the area of the concave portion is small ascompared to that shown in FIGS. 10A and 10E. In FIG. 10B, a conductivematerial 1006 and a barrier metal 1007 form the bonding portion 311B. Inaddition, the upper face of the second wiring structure has an upperface 1001 of the interlayer insulating film, a concave portion 1002, andan upper face 1003 of a part of the bonding portion 311B. In the concaveportion 1002, the bottom face is a part of an upper face 1005 of thebonding portion 311B, and the bonding portion 311B is exposed at a sideface 1004. In addition, the upper face 1001 of the interlayer insulatingfilm 127 and the upper face 1005 of the bonding portion 311B at theconcave portion form a step d1. As shown in FIG. 10F, the concaveportion 1002 has an area smaller than that of the bonding portion 311B.The structure as described above is also applicable to the concaveportion of the present invention.

Next, Modification 2 will be described with reference to FIGS. 10C and10G. FIGS. 10C and 10G are a schematic cross-sectional view and aschematic plan view, respectively, corresponding to each other and showa smooth concave shape as compared to that shown in FIGS. 10A and 10E.In FIG. 10C, a conductive material 1012 and a barrier metal 1013 formthe bonding portion 311B. In addition, the upper face of the secondwiring structure has an upper face 1008 of the interlayer insulatingfilm and a concave portion 1009. The concave portion 1009 is differentfrom the concave portion 704 shown in FIG. 10A, and the step has not aside face and has a concave shape with a curvature. A bottom face of theconcave portion 1009 contains an upper face 1010 of a part of theinterlayer insulating film 127 and an upper face 1011 of the bondingportion 311B. In addition, the concave portion 1009 has a step up to d1between the upper face 1008 of the interlayer insulating film 127 andthe upper face 1011 of the bonding portion 311B. In FIG. 10G, theconcave portion 1009 has an area larger than that of the bonding portion311B. A concave portion having the structure as described above can beobtained, in particular, by performing a CMP treatment. The structure asdescribed above is also applicable to the concave portion of the presentinvention.

Next, Modification 3 will be described with reference to FIGS. 10D and10H. FIGS. 10D and 10H are a schematic cross-sectional view and aschematic plan view, respectively, corresponding to each other, and asmall concave portion as compared to that shown in FIGS. 10C and 10G isformed. In FIG. 10D, a conductive material 1018 and a barrier metal 1019form the bonding portion 311B. In addition, the upper face of the secondwiring structure has an upper face 1014 of the interlayer insulatingfilm, a concave portion 1015, and an upper face 1016 of a part of thebonding portion 311B. A bottom face of the concave portion 1015 containsan upper face 1017 of the bonding portion 311B. In addition, the concaveportion 1015 has a step up to d1 between the upper face 1014 of theinterlayer insulating film 127 and the upper face 1017 of the bondingportion 311B. In FIG. 10H, the concave portion 1015 has an area smallerthan that of the bonding portion 311B. A concave portion having thestructure as described above can be obtained, in particular, byperforming a CMP treatment. The structure as described above is alsoapplicable to the concave portion of the present invention.

As described above, as the structure of the concave portion of the upperface, a concave portion having a step as shown in FIG. 10A, a concaveportion having a curvature as shown in FIG. 10C, and other arbitrarystructures may be used. In addition, a step having an arbitrary size maybe selected for each member. When the bonding portion 311B is viewedfrom the above in a direction perpendicular thereto, that is, in a planelayout, a plurality of concave portions each having an arbitrary shapemay also be formed. Of course, it is possible to apply the structure ofthe concave portion of the upper face shown in each of FIGS. 10A to 10Hto the first wiring structure.

Hereinafter, as one application example of the solid-state image pickupdevice of each of the above embodiments, an image pickup systemincorporating a solid-state image pickup device will be described by wayof example. In the image pickup system, besides devices, such as acamera, primarily used to pickup images, devices (such as a personalcomputer and a personal digital assistant) auxiliary having an imagepickup function are also included. For example, a camera includes thesolid-state image pickup device of the present invention and aprocessing portion which processes a signal outputted from thesolid-state image pickup device. This processing portion may include,for example, an A-D converter and a processor processing a digital dataoutputted therefrom.

As has thus been described, according to the method for manufacturing asolid-state image pickup device of the present invention, a member for asolid-state image pickup device having a bonding structure which enablesa bonding plane to be flat after bonding and a method for manufacturingthe same can be provided.

In addition, the present invention is not limited to the structuresdescribed in the specification and may also be applied, for example, tothe case in which the pixel circuit is changed, only the photoelectricconverters are arranged on the first member, and/or all the pixelcircuits are arranged thereon. Furthermore, the present invention may beappropriately applied, for example, to the structure in which theconductive and/or circuit type is changed to a reversed type, thestructure in which a wiring layer and an interlayer insulating film arefurther provided, and the case in which a single damascene structure ischanged to a dual damascene structure. In addition, the structures ofthe above embodiments may also be used in combination. In the presentinvention, the concave portion may be provided for at least one ofmembers, and the shape of the upper face of the other member is notparticularly limited.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2010-156927, filed Jul. 9, 2010, which is hereby incorporated byreference herein in its entirety.

REFERENCE SIGNS LIST

301 pixel portion

302 peripheral circuit portion

308 first member

309 second member

149 first wiring structure

150 second wiring structure

311 bonding portion

312 pad portion

313 pad

101 first substrate

121 second substrate

100 opening

X bonding plane

The invention claimed is:
 1. A method for manufacturing a solid stateimage pickup device, comprising the steps of: providing a first memberincluding a first substrate and a first wiring structure disposed on thefirst substrate, the first substrate being provided with at least one ofa transistor and a photoelectric converter; providing a second memberincluding a second substrate and a second wiring structure disposed onthe second substrate, the second substrate being provided with atransistor; and bonding the first member and the second member so thatthe first wiring structure and the second wiring structure are disposedbetween the first substrate and the second substrate, wherein before thestep of bonding, at least one of a face of the first member which is toface the second member and a face of the second member which is to facethe first member has a concave portion, and at least a part of theconcave portion is formed by a conductive material.
 2. The method formanufacturing a device according to claim 1, wherein at least one of thestep of providing the first member and the step of providing the secondmember comprises the substeps of: forming an insulating film on asemiconductor substrate; forming a conductive material on thesemiconductor substrate; and forming the concave portion in a faceformed by the insulating film and the conductive material.
 3. The methodfor manufacturing a device according to claim 2, wherein the substep offorming the concave portion includes removing a part of the conductivematerial.
 4. The method for manufacturing a device according to claim 2,wherein the substep of forming the concave portion includes removing apart of the insulating film.
 5. The method for manufacturing a deviceaccording to claim 2, wherein the substep of forming the concave portionincludes removing a part of the first insulating film.
 6. The method formanufacturing a device according to claim 2, wherein the substep offorming the conductive material includes filling the conductive materialand a barrier metal in a groove of the insulating film.
 7. The methodfor manufacturing a device according to claim 1, wherein a part of theconcave portion is formed by an insulating material.
 8. The method formanufacturing a device according to claim 1, wherein a primary componentof the conductive material is copper.
 9. The method for manufacturing adevice according to claim 1, wherein the first wiring structure has afirst portion which forms the face of the first member, and the secondwiring structure has a second portion which forms the face of the firstmember, and an electrical connection between the first member and thesecond member is formed by bonding the first portion and the secondportion in the step of bonding, and wherein at least one of the firstportion and the second portion forms at least the part of the concaveportion.
 10. The method for manufacturing a device according to claim 1,wherein before the step of performing bonding is performed, at least oneof the face of the first member and the face of the second member isirradiated with plasma.
 11. The method for manufacturing a deviceaccording to claim 1, wherein the step of performing bonding isperformed in a vacuum or an inert gas atmosphere.
 12. The method formanufacturing a device according to claim 1, wherein the first substrateis provided with the photoelectric converter and the second substrate isprovided with an amplification transistor outputting a signal based on acharge of the photoelectric converter and a reset transistor resettingthe charge of the photoelectric converter on the second substrate. 13.The method for manufacturing a device according to claim 9, wherein aprimary component of the first bonding portion and a primary componentof the second bonding portion are copper.
 14. The method formanufacturing a device according to claim 1, wherein before the step ofbonding, the face of the first member has a concave portion, at least apart of which is formed by a conductive material, and the face of thesecond member has a concave portion, at least a part of which is formedby a conductive material, and in the step of bonding, the concaveportion of the face of the first member faces the concave portion of theface of the second member.
 15. The method for manufacturing a deviceaccording to claim 1, wherein one of the face of the first member andthe face of the second member has a concave portion, at least a part ofwhich is formed by a conductive material, wherein the other of the faceof the first member and the face of the second member has a convexportion, at least a part of which is formed by a conductive material,and wherein in the step of bonding, the concave portion of one of theface of the first member and the face of the second member faces theconvex portion of the other of the face of the first member and the faceof the second member.
 16. The method for manufacturing a deviceaccording to claim 1, wherein in the step of bonding, a conductivematerial in the face of the first member and a conductive material inthe face of the second member contacts with each other, and aninsulating material in the face of the first member and an insulatingmaterial in the face of the second member contact with each other. 17.The method for manufacturing a device according to claim 1, wherein thestep of bonding includes performing a heat treatment.
 18. The method formanufacturing a device according to claim 1, further comprising, afterthe step of bonding, a step of reducing a thickness of the firstsubstrate.
 19. The method for manufacturing a device according to claim1, wherein the first substrate is provided with the photoelectricconverter and a transfer transistor transferring a charge of thephotoelectric converter.